Perhaps you should try some spelling variations:
perv » per (Expand Search)
petro » petrov (Expand Search), petri (Expand Search), petru (Expand Search), petero (Expand Search), petrio (Expand Search), petruo (Expand Search)
peri » petri (Expand Search), per (Expand Search)
petruv » peteruv (Expand Search), petriuv (Expand Search), petruuv (Expand Search)
petriiv » peteriiv (Expand Search), petriiiv (Expand Search), petruiiv (Expand Search)
petruio » peteruio (Expand Search), petriuio (Expand Search), petruuio (Expand Search)
petr » peter (Expand Search), petri (Expand Search), petru (Expand Search)

Try widening your search to All Fields.

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: fop ((petruv OR (perv OR petriiv)) OR ((((petro OR petruio) OR petero) OR peri) OR petr)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((petruv OR (perv OR petriiv)) OR ((((petro OR petruio) OR petero) OR peri) OR petr)) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((petruv OR (perv OR petriiv)) OR ((((petro OR petruio) OR petero) OR peri) OR petr)) o.s.*.